Release notes:

"xserver-xorg-core now uses libseat1 to control rootless startx and access to input and video devices. This has several advantages, the most significant being that it removes the dbus dependency from xserver-xorg-core."

https://files.devuan.org/devuan_daedalus/Release_notes.txt

Never took the time to have a look for it: have xorg the priviledge dropping code or do I have to start it with the priviledges already dropped?

Good to see Devuan is still alive and has some solutions to systemd plague.